This invention generally relates to solar energy collectors. More particularly, this invention relates to a solar energy collector of the type using an array of tubular collector elements. Specifically, this invention relates to such a solar energy collector which has a specific relationship of tube spacing to tube diameter and of tube distance from a diffusely-reflecting surface.
The use of tubular collector arrays for the collection of solar energy is known in the art. See, for example, U.S. Pat. Nos. 980,505 and 2,133,649. I have found that a diffuse-reflecting surface positioned behind a tubular solar energy collector array can significantly increase the efficiency. See U.S. Pat. No. 2,213,894 for an example of a diffuse reflector in the prior art. I have further found that if the tubes are spaced no farther apart than four tube diameters on centers and no more than four tube diameters away from the diffuse-reflecting surface, that maximum efficiencies may be achieved.